Conscript: console scripts in your own Swiss Army Knife.

Conscript provides a console script you can use to conveniently expose all other console scripts in a virtual environment. In a traditional virtual environment this is of little use. In a zipapp, it gives you capabilities similar to BusyBox.

Use

To create a BusyBox, simply add conscript to your dependencies and set your application main entrypoint to the conscript console script.

Examples

Examples are probably the best way to demonstrate the utility of Conscript. Both Pex and Shiv are popular tools for creating zipapps with third party dependencies; so they lead to concise examples.

Pex

1. Create the BusyBox PEX zipapp:

   $ pex cowsay fortune conscript --script conscript --output-file speak

2. Examine the available embedded apps:

   $ ./speak -h
   usage: speak [-h] [PROGRAM]
   
   A speak busy box.
   
   positional arguments:
     PROGRAM     The program to execute.
   
                 The following programs are available:
                 + cowsay
                 + fortune
   
   optional arguments:
     -h, --help  Show this help message and exit.

3. Run an embedded app:

   $ ./speak cowsay "Conscript is my Swiss Army Knife!"
     _________________________________
   | Conscript is my Swiss Army Knife! |
     =================================
                                    \
                                     \
                                       ^__^
                                       (oo)\_______
                                       (__)\       )\/\
                                           ||----w |
                                           ||     ||

4. Or another one:

   $ ./speak fortune -h
   Usage: speak [OPTIONS] [fortune_file]
   
   Options:
     -h, --help     show this help message and exit
     -V, --version  Show version and exit.
   
   If fortune_file is omitted, fortune looks at the FORTUNE_FILE environment
   variable for the path.
   $ ./speak fortune /usr/share/fortune/science
   Nondeterminism means never having to say you are wrong.

5. Target an embedded app via a symlink:

   $ ln -s speak cowsay
   $ ./cowsay Nifty.
     ______
   | Nifty. |
     ======
         \
          \
            ^__^
            (oo)\_______
            (__)\       )\/\
                ||----w |
                ||     ||

Shiv

The capabilities exposed by Conscript are the same as in the Pex example, so this example is abbreviated to the basics. The primary difference is that Shiv does not fully isolate requested dependencies in the zipapp from incidental dependencies and so we see more available console scripts than in the Pex case.

1. Create the BusyBox shiv zipapp:

   $ shiv cowsay fortune conscript --python '/usr/bin/env python' --console-script conscript --output-file say
   Collecting cowsay
     Using cached cowsay-4.0-py2.py3-none-any.whl (24 kB)
   Collecting fortune
     Using cached fortune-1.1.0-py2.py3-none-any.whl (5.9 kB)
   Collecting conscript
     Using cached conscript-0.1.1-py2.py3-none-any.whl (7.5 kB)
   Collecting grizzled-python>=1.0
     Using cached grizzled_python-2.2.0-py2.py3-none-any.whl (36 kB)
   Installing collected packages: grizzled-python, fortune, cowsay, conscript
   Successfully installed conscript-0.1.1 cowsay-4.0 fortune-1.1.0 grizzled-python-2.2.0

2. Use it:

   $ ./say -h
   usage: say [-h] [PROGRAM]
   
   A say busy box.
   
   positional arguments:
     PROGRAM     The program to execute.
   
                 The following programs are available:
                 + cowsay
                 + easy_install
                 + easy_install-3.8
                 + fortune
                 + pip
                 + pip3
                 + pip3.8
                 + shiv
                 + shiv-info
   
   optional arguments:
     -h, --help  Show this help message and exit.
   $ ./say cowsay --version
   4.0